Our long-term objective is to establish the functional significance of somatosensory neurons in the parietal association cortex of monkeys. Our hypothesis is that somatosensory, visuosensory and task-related neurons in area 7b (PF) of the inferior parietal lobule are a spatially and temporally coordinated neuronal ensemble that can provide continuous sensory information about the general location of a potentially noxious stimulus and its rate of motion in extrapersonal space and about the general location of a potentially noxious or frankly noxious stimulus and its rate of intensity change in personal space. We also propose that this polysensory neuronal assembly in area 7b is associated with attention- related behaviors such as orienting to sensory events and is modulated itself by stimulus modality-selective attention. The first objective of this project is to quantitatively delimit the sensory response properties of area 7b neurons and especially, the capacity by which somatosensory neurons can provide information about stimulus location, intensity and rate. A detailed characterization of these sensory response properties is needed for designing future experiments that will elucidate the role of area 7b in specific attention-related behaviors. We will use calibrated thermal stimulation of the face and monkeys trained to perform an appetitive tolerance-escape task to determine the stimulus- response functions of somatosensory neurons. Particular emphasis is given to characterizing nociceptive responses and correlating such responses to thermal pain tolerance threshold and magnitude. The second objective of this project is to assess the effects of stimulus modality-selective attention on the thermal responses of somatosensory and task-related neurons, and on the pain tolerance threshold and magnitude. Selective attention directed toward a non-threatening visual stimulus as opposed to a threatening thermal stimulus may produce different effects on neuronal responses and pain behavior. Monkeys will be trained to perform a modified appetitive tolerance-escape task that incorporates a stimulus modality attention sub-task. The neurobehavioral experiments that we propose to perform will provide a quantitative description of area 7b neuronal response properties and of the modulation of these properties of stimulus modality-selective attention. A synthesis of information regarding the functional significance and connectivity of area 7b will provide a better understanding of how the parietal cortex subserves the different dimensions of pain experience.